Hydrogen Bonding Interactions in Metal Complexes

Hydrogen bonding in metal complexes encompasses a spectrum of noncovalent interactions in which hydrogen atoms bound to electronegative donor groups (for example O–H, N–H or even C–H) engage directly with metal centres. Rather than forming conventional covalent bonds, these interactions arise from electrostatic attraction, partial charge transfer and orbital overlap, leading to stabilisation of coordination assemblies. Such bonding motifs are found in catalysts, supramolecular frameworks and biological metalloenzymes, where they influence reactivity, selectivity and structural rigidity. In many cases, weak C–H···M contacts can complement stronger O–H···M or N–H···M bonds, producing complex networks that govern substrate binding and stabilise transition states. Advances in spectroscopic, crystallographic and computational techniques have revealed that late-transition metals—including gold, silver and copper—can act as unexpected hydrogen-bond acceptors, expanding the classical view of hydrogen bonding. Understanding these subtleties enables the rational design of functional materials, tailored catalysts and robust metal-organic frameworks with predictable properties.

Research from Nature Portfolio

Recent studies have provided definitive evidence of hydrogen bonds to gold atoms in coordinated clusters. Spectroscopic and crystallographic analyses of hexagold species decorated by diphosphine ligands revealed C–H···Au distances significantly shorter than van der Waals radii, accompanied by downfield shifts in NMR signals that confirm attractive interactions. These findings demonstrate that partially oxidised gold centres can serve as bona fide acceptors of hydrogen bonds, playing a critical role in cluster stability and ligand organisation. In parallel, investigations of subnanometre gold catalysts have shown that dispersive Au···C–H and Au···π interactions synergise to stabilise very small gold clusters during catalytic hydration of alkynes. Time-resolved luminescence and quantum-mechanical calculations indicate that these weak hydrogen-bond-like contacts can be fine-tuned by substituent effects, leading to remarkably active and durable catalytic systems.

Hydrogen Bonding Interactions in Metal Complexes publication trend

The graph below shows the total number of articles in hydrogen bonding interactions in metal complexes across all publications each year (not limited to Nature Index journals).

Technical terms

Hydrogen bond: A noncovalent attraction between a hydrogen atom bonded to an electronegative donor and an electron-rich acceptor, here often a metal centre.

Noncovalent interaction: A reversible, weak force (electrostatic, van der Waals or π-type) that does not involve sharing of electron pairs as in covalent bonds.

Donor: An electronegative atom or group (for example O–H, N–H or C–H) that provides a hydrogen atom for interaction.

Acceptor: An electron-rich site, such as a metal centre or π-system, that engages in attractive interactions with a hydrogen donor.

Ligand: A molecule or ion bound to a metal centre, which can modulate hydrogen bonding through its donor atoms and substituents.

π-System: A delocalised set of p-orbitals, often in aromatic rings or unsaturated ligands, capable of engaging in secondary interactions with hydrogen or metals.

References

1. Hydrogen bonds to Au atoms in coordinated gold clusters. Nature Communications (2017).
2. The key role of Au-substrate interactions in catalytic gold subnanoclusters. Nature Communications (2017).
3. Can Copper(I) and Silver(I) be Hydrogen Bond Acceptors?. Chemistry - A European Journal (2023).
4. Comparison of Conventional and Nonconventional Hydrogen Bond Donors in Au– Complexes. The Journal of Physical Chemistry A (2022).